On an Escher the same size, shape & box I had the label come off and I put it away. On some Eschers you'll find that the surface under the label side is very irregular. Sort of rough hewn. I've got more than one like that.

That is the way the stone I'm talking about is so I only lapped the one side. Yours may be different and lend itself to flattening but I would still leave the label side as is even with the label set aside. Obviously YMMV.